Oxidative stress is defined as an imbalance in pro-oxidants and antioxidants with associated disruption of redox circuitry and macromolecular damage. Chronic oxidative stress is believed to increase the risk of many cancers such as breast and colorectal cancers. Despite being at increased risk of developing and dying from oxidative-stress related cancers, African-Americans are under-represented in population-based studies of oxidative stress and cancer. This is especially true for biomarker-based and nutritional epidemiology studies of oxidative stress. This career development award is designed to provide training and research experience to Dr. Dash to support his goal of becoming an independent researcher investigating the molecular epidemiology of cancers among minorities including cancer disparities. Proposed training plans include mentorship and coursework in proteomics, metabolomics, bioinformatics, and exploratory data analysis, filling gaps in research training related to studies among minorities and health disparity studies, and research considerations in recruitment and bio specimen collection from minorities in epidemiologic research. The research component of the proposal aims to address the research gaps mentioned above by (1) characterizing the systemic oxidative stress burden via measurement of a panel of known biomarkers of oxidative stress using proteomics and metabolomics technologies; (2) identifying dietary patterns associated with oxidative stress; and (3) investigating the association of these dietary patterns with risk of breast and colorectal cancers among African- American women. The study will be conducted in two phases. Phase 1 involves measurement of a panel of 6 oxidative stress biomarkers using proteomic and metabolomic approaches and describing the oxidative stress burden among African-American women without cancer. Dietary patterns related to the biomarkers of oxidative stress will also be identified usin dietary intake data self-reported by participants on food frequency questionnaires. Phase 2 of the study involves investigating the association of the oxidative stress-related dietary patterns developed in Phase 1 with breast and colon cancer risk in a large, nationally-representative, cohort study of Black women. Results from the study will support larger and more definitive studies on oxidative stress and cancer among African-American women. The proposed research complements the training and mentorship plans in proteomics, metabolomics, bioinformatics, biostatistics, and minority health research. With this award Dr. Chiranjeev Dash will combine his previous training in epidemiology with advanced training in metabolomics/proteomics, bioinformatics, and biostatistics, and gain experience in conduct of minority health research to establish an independent research career focusing on translational research on the molecular epidemiology of oxidative stress in cancer causation and prevention.